Connected: An Internet Encyclopedia
RFC 1112 - 7.4. Extensions to an Ethernet Local Network Module

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### 7.4. Extensions to an Ethernet Local Network Module

To support the reception of multicast IP datagrams, an Ethernet module must be able to receive packets addressed to the Ethernet multicast addresses that correspond to the host's IP host group addresses. It is highly desirable to take advantage of any address filtering capabilities that the Ethernet hardware interface may have, so that the host receives only those packets that are destined to it.

Unfortunately, many current Ethernet interfaces have a small limit on the number of addresses that the hardware can be configured to recognize. Nevertheless, an implementation must be capable of listening on an arbitrary number of Ethernet multicast addresses, which may mean "opening up" the address filter to accept all multicast packets during those periods when the number of addresses exceeds the limit of the filter.

For interfaces with inadequate hardware address filtering, it may be desirable (for performance reasons) to perform Ethernet address filtering within the software of the Ethernet module. This is not mandatory, however, because the IP module performs its own filtering based on IP destination addresses.

Next: 7.5. Extensions to Local Network Modules other than Ethernet

Connected: An Internet Encyclopedia
RFC 1112 - 7.4. Extensions to an Ethernet Local Network Module